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Find the sum of the first 50 terms of the arithmetic sequence if the first term is 21 and the twentieth term is 154.​

Answers

  • Réponse publiée par: shannel99

    9625

    Step-by-step explanation:

    for an arithmetic sequence

    ●an = a + (n-1) d

    ●sn = n/2[2a + (n-1)d]

    where is the first term and d the common difference we require to find d

    given: a=21 then

    a20=21 + 19d = 154

    19d = 154 - 21 = 133 d= 133/19 = 7

    s50 = 50/2 [(2x21) + (49×7)]

    =25(42 + 343)

    =25 × 385=9625

  • Réponse publiée par: elaineeee

    answer:

    50th term is D. 9625 Explanation:

    for an arithmetic sequence

    ∙xan=a+(n−1)d∙xSn=n2[2a+(n−1)d

    ]

    where a is the first term and d the common difference

    we require to find d

    given

    a=21 then

    a20=21+19

    d=15419

    d=154-21=133

    d=13319=7

    S50=502[(2×21)+(49×7)]

    ×=25(42+343)×=25×385=9625

  • Réponse publiée par: villatura

    b.9765

    Step-by-step explanation:

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  • Réponse publiée par: hajuyanadoy

    find the sum of the first 50 terms of the arithmetic sequence if the first term is 21 and the twentieth term is 154

    answer

    9625

    Step-by-step explanation:

    for an arithmetic sequence

    ●an = a + (n-1) d

    ●sn = n/2[2a + (n-1)d]

    where is the first term and d the common difference we require to find d

    given: a=21 then

    a20=21 + 19d = 154

    19d = 154 - 21 = 133 d= 133/19 = 7

    s50 = 50/2 [(2x21) + (49×7)]

    =25(42 + 343)

    =25×385=9625

  • Réponse publiée par: saintjohn

    Hope this helps!

    #CarryOnLearning


    Find the sum of the first 50 terms of the arithmetic sequence if the first term is 21 and the twenti
  • Réponse publiée par: reyquicoy4321

    Step-by-step explanation:

    9625

    I used other steps. Since first term is 21 and 20th term is 154 its common difference was 7. Using 49 multiplied to 7 and adding 21 you can get the last term 364.By adding last and first and multiply it by 25 you can get the sum of 9625. Hope this helps.

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Find the sum of the first 50 terms of the arithmetic sequence if the first term is 21 and the twenti...